In many gas fired furnaces as much as 60 percent of the heat supplied is wasted because it is discharged up the exhaust stack before it is circulated or otherwise utilized for its intended purpose. This is a great loss of energy which is even more aggravating with the present scarcity of fuel in many of the major industrial countries.
While various heat exchangers, recuperators and other devices have been suggested to utilize this wasted gas, most of these prior art devices are complex, expensive and require major alterations to existing furnaces. While recuperators located externally of the combustion system have also been used, external recuperators are usually bulky and occupy valuable storage space. Typifying some of the many conventional heat exchangers and other prior art devices are those shown in British Pat. Nos. 1,010,870, 1,301,669 and 1,492,520.
It is therefore desirable to provide an improved apparatus which overcomes most, if not all, of the preceding problems.